The invention pertains to methods and apparatuses for increasing dissolved gas concentrations in liquids and to methods of providing liquids for semiconductive wafer fabrication processes, such as polishing systems. The invention also pertains to methods of cleaning polishing slurry from semiconductive substrate surfaces.
In many semiconductive material fabrication processes it is desirable to utilize deionized and degassed water. The deionization is used to remove elemental contaminants from the water and can increase a resistance of the water to from about 200 kohms to about 1800 kohms.
The degassification is used to remove carbon dioxide from the water. Carbon dioxide can influence a pH of the water. The degassification also, however, removes other gasses from water besides carbon dioxide. Such other gasses can include, for example, oxygen and nitrogen. An example unit for degassifying water is a Liquicell unit (available from Hoechst Celanese Corp. at 13800 South Lake Drive, Charlotte, N.C. 28273), which removes gasses via a gas permeable membrane.
The deionization and degassification of water is typically done on a system-wide scale in a semiconductive material fabrication plant. Accordingly, all water supplied to the various fabrication units of the plant is degassed and deionized.
The invention encompasses methods and apparatuses for increasing dissolved gas concentrations in liquids, and methods of providing liquids for semiconductive wafer fabrication processes, such as polishing systems. The invention also encompasses polishing systems for polishing semiconductive material substrates, and methods of cleaning polishing slurry from semiconductive substrate surfaces.
In one aspect, the invention encompasses a method of preparing a liquid for a semiconductor fabrication process. A liquid is provided, and a gas is injected into the liquid to increase a total dissolved gas concentration in the liquid.
In another aspect, the invention encompasses a method of cleaning a polishing slurry from a substrate surface. A substrate surface is provided, and a polishing slurry is provided in contact with the substrate surface. A liquid is provided. A gas is injected into the liquid to increase a total dissolved gas concentration in the liquid. After the injecting, the liquid is provided against the substrate surface to displace the polishing slurry from the substrate surface.
In yet another aspect, the invention encompasses a method of polishing a substrate surface. A polishing slurry is provided between a substrate surface and a polishing pad. The substrate surface is polished with the polishing slurry. The polishing slurry is removed from the substrate surface. The removing comprises the following. A liquid is provided. A first gas is removed from the liquid to reduce a total dissolved gas concentration in the liquid. After removing the first gas, a second gas is dissolved in the liquid to increase the total dissolved gas concentration in the liquid. After dissolving the second gas, the liquid is provided between the substrate surface and the polishing pad to displace the polishing slurry from the substrate surface.